PCT International No. WO 94-08 236 describes a method for manufacturing an optical cover component for an integrated optical circuit. The optical component is placed in a molding die. Using an injection molding or injection embossing method, a curable liquid is introduced into a desired mold around the optical component and cured. The embedded optical component is then unmolded.
German Patent Application No. P 44 34 832.0 describes a trough-shaped container, which is placed with its opening downward on a molding die, in order to manufacture an integrated optical cover component. A liquid reaction molding compound is introduced into the interior of the trough-shaped container, and is solidified by heating. The cover component is then unmolded.
Microstructured reaction-molded elements commonly have shearing defects whose origin is attributable to a distortion present between the mold insert and the molded element during unmolding. The occurrence of this distortion is attributable to a change over time, between the mold formation time and the mold separation time, in the temperature of the system of plastic + mold insert, since the plastic has a different coefficient of thermal expansion than the metal mold. The shrinkage which occurs in reaction molding has a negative influence on the shaping of the cast element, due to the occurrence of shrinkage cavities.
Microstructures have until now been manufactured principally with the injection-molding method. The "Variotherm" method was developed to overcome the above disadvantages. For technical or commercial reasons, a number of materials that are of great interest for optical applications (crosslinked polymers, including very expensive special halogenated monomers) cannot be processed by injection molding.